1. Field of the Invention
This invention generally relates to a roll back seal for a disc brake. More specifically, the present invention relates a roll back seal that reliably returns a piston to a release position from a braking position with improved sealing characteristics over a longer service life.
2. Background Information
Bicycling is becoming an increasingly popular form of recreation as well as a means of transportation. Moreover, bicycling has become a very popular competitive sport. Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving their components. One particular component of the bicycle, which has been extensively redesigned over the past years, is the braking systems of bicycles. In particular, the braking power of the braking systems is constantly being increased.
There are several types of bicycle brake devices, which are currently available on the market. Examples of some types of common bicycle brake devices include rim brakes, caliper brakes and disc brakes. If a rider wants a very high performance brake system, then the rider typically wants a disc brake system. Disc brake systems provide a substantial braking power in relationship to the amount of braking force applied to the brake lever. Moreover, disc brake systems typically provide a high level of consistency in all types of weather and riding conditions. Of course, riders constantly desire better performance from disc braking systems, i.e., disc brake systems that have more braking power.
Conventionally, a disc brake is composed of a pair of brake pads that are movably mounted to a caliper housing. The brake pads are pressed against a disc or rotor that is fixed to the wheel to halt the rotation of the disc and thus the wheel. The brake pads are moved toward the disc hydraulically or mechanically such as by a cam mechanism. The hydraulic disc brake systems typically provide a high level of consistency in all types of weather and riding conditions.
In some hydraulic disc brakes, the seal rings are used to return the pistons from the braking position to the release position. These seal rings do not always reliably return the pistons to the release position which can cause rubbing between the friction pads and the rotor. Moreover, after extended use, these seal rings can become worn and/or fail, which can allow hydraulic fluid to leak from the disc brake assembly.
In view of the above, there exists a need for roll back seal for a disc brake assembly which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
One object of the present invention is to provide a roll back seal that reliably returns a piston from a braking position to a release position.
Another object of the present invention is to provide a roll back seal with improved sealing characteristics over a longer service life.
Yet another object of the present invention is to provide a roll back seal that is relatively simple and inexpensive to manufacture and assemble.
The foregoing objects can basically be obtained by providing a disc brake assembly with an annular roll back seal. The disc brake assembly includes a caliper housing with a piston receiving opening, a first and a second friction member coupled to the caliper housing, a piston movably coupled in the piston receiving opening and the annular roll back seal. The piston receiving opening has an annular side wall with an annular groove formed therein. The first and second friction members form a rotor receiving slot between the first and second friction members. At least the first friction member is movably coupled to the caliper housing. The piston movably coupled in the piston receiving opening of the caliper housing moves the first friction member between a release position and a braking position. The annular roll back seal is located in the annular groove between the caliper housing and the piston. The roll back seal includes a first annular end surface, a second annular end surface, an inner annular sealing surface and an outer annular sealing surface. The second annular end surface is spaced from the first end surface. The inner annular sealing surface extends between the first end surface and the second end surface. The outer annular sealing surface extends between the first end surface and the second end surface. The second end surface has an annular recess formed therein.
These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention.